How would Texas determine whether they secede or not?

Texas cannot legally secede from the United States. The Supreme Court ruled in the case of Texas v. White (1869) that the act of secession was "an illegal act, and that it had never acquired any legal validity." This decision has been upheld in subsequent cases, and it is now considered to be settled law that states cannot unilaterally secede from the United States.

If Texas were to attempt to secede, the United States government would likely take steps to prevent it. These steps could include military intervention, economic sanctions, and diplomatic pressure. The United States government has a strong interest in preserving the Union, and it has shown a willingness to use force to do so.

In addition to the legal and political obstacles to secession, there are also practical challenges. Texas is a large state with a population of over 28 million people. Secession would require a massive logistical effort, and it would likely be very disruptive to the economy. For these reasons, it is highly unlikely that Texas will ever secede from the United States.